Two-dimensional analysis for non-equilibrium homogeneously condensing flows through steam turbine cascade

Abstract

A computational technique for the two-dimensional non-equilibrium homogeneously condensing flows through steam turbine cascades is presented. The fundamental equations of compressible wet steam flows are descretized based on the TVD scheme and following thermodynamic assumptions. 1) The gas phase is an ideal gas. 2) A liquid phase consists of droplets whose radii are in the order of 10-6m or less, thereby, the wet steam is a homogeneous fluid. 3) A gas-liquid phases are changed by the homogeneous nucleation and growth of the existing droplets, which are described by the classical nucleation theory. In this theory, a driving force of a phase change is a degree of supercooling. The described assumptions are valid for the flow through the low-pressure stage of the steam turbines. Flow through the moving blades for a low-pressure steam turbine is calculated. The calculated pressure distributions on the blade surface agree well with experimental data. The influences of both the degree of inlet supercooling and the ratio of the inlet total pressure to outlet static pressure on the blade performance, mass flow, flow angle, energy loss are studied.